Wire bending device

ABSTRACT

The invention concerns a wire bending device comprising a bending head ( 3 ) bearing two bending tools ( 30, 31 ) between which the wire to be bent ( 2 ) is passed, each of the tools being capable of being driven in rotation concentrically around the other which is then fixed It comprises: mechanical means ( 1 ) for moving the wire to be bent ( 2 ) axially in one direction or another (X A , X B ); mechanical mans for driving the tools ( 30, 31 ) in rotation, in the two directions (Y A , Y B ), about an axis ( 34 ) parallel to those ( 32, 33 ) of the tools ( 30, 31 ); mechanical means for moving in the two directions (Z A , Z B ) the tools ( 30, 31 ) in a plane perpendicular to the axis ( 34 ) about which the latter can rotate; and calculating and controlling means for managing simultaneously the operation of the mechanical means so that the movements generated by the latter are superimposed.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The present invention relates to a wire bending device.

DESCRIPTION OF THE PRIOR ART

[0003] There are presently two large categories of wire bending machines, those used for large series that comprise bending tools placed in a position corresponding to the profile to be imparted to the metal wire, and those used for small series that permit to pass from one profile to another without it being necessary, in contrast to the preceding ones, to change tools.

[0004] All the machines of this second category make use of the same bending method consisting in passing the wire between two bending tools, of which one is fixed and the other is mobile in rotation concentrically in relation to the fixed one.

[0005] Practically, the wire coming from a reel or a coil passes through a straightener, then is picked up by a feeding system bringing the desired length of it to a bending head, which is generally mobile in rotation around the wire's axis, and comprising a fixed catch for maintaining the wire and a bending roller capable of rotating concentrically about the catch, in order to bend the wire.

[0006] Changing of the curving direction is achieved by changing the starting position of the catch and the roller, the positions of which are reversed with respect to the wire, which is carried out by means of an axial rotation around the wire or, in case said rotation is not possible, by means of displacement after their retraction into the head.

[0007] These numerical control machines are very flexible in use, and permit producing series of pieces ranging from several dozens to several thousands.

[0008] Victims of their success, they are used for larger series, since, with experience, their programming becomes easy.

[0009] Nevertheless, for large series, one quickly finds out that they are slow, because of the retraction time for the roller and the catch, which represents about 40% of the overall time of a bending operation.

[0010] In order to cope with this drawback, it has been proposed, in particular in FR 2,744,941, to pass the wire to be bent between two rollers, each one capable of being driven in rotation concentrically around the other one, which is fixed in this case.

[0011] This method avoids the retraction periods of the bending roller, since both rollers can at will become alternatively bending roller or fixed catch for maintaining the wire.

[0012] In order to implement this method, there has been proposed in this document a device comprising, in a bending head mobile in rotation around the wire's axis, on the one hand, two parallel shafts, between which passes transversally, externally with respect to said bending head, the wire to be bent, said shafts being connected through a part comprising two identical gears integral with each other, not coaxially, by their flanks, said shafts crossing, each, axially and jointly one of said gears; on the other hand, for each of said shafts, a guiding path in the shape of an arch of a circle, the guiding path of a shaft being coaxial in relation to the other shaft; and yet on the other hand, a gear driven in rotation in one direction or in the other, positioned in the region in front of the concave portions of said guiding paths and such as to mesh with said gears.

[0013] This device is relatively complex and has the drawback of being unreliable in the course of time.

[0014] This lack of reliability is increased in that the steering of the shafts in the guiding paths is made through sliding runners suffering from wearing problems.

SUMMARY OF THE INVENTION

[0015] This invention aims at coping with this drawback by providing a bending device operating according to the same method, said device being a more robust and therefore more reliable design.

[0016] The wire bending device this invention refers to is of the type comprising one bending head carrying two bending tools between which passes the wire to be bent, each one of said tools being capable of being driven in rotation concentrically around the other one, which is fixed in this case, and it is characterized essentially in that it comprises:

[0017] mechanical means capable of shifting the wire to be bent axially in one direction or another,

[0018] mechanical means capable of driving said bending tools in rotation, in both directions, around an axis parallel to that of said tools,

[0019] mechanical means capable of shifting, in both directions, said tools in a plane perpendicular to the axis around which the latter can rotate,

[0020] and computation and control means capable of governing the simultaneous operation of said mechanical means, so as to obtain a superposition of the movements the latter generate.

[0021] The superposition of the movements generated by the various mechanical means permits carrying out, in a relative manner, the positioning and the immobilization of one of the tools in relation to the wire to be bent, while causing the other tool to rotate concentrically about the immobilized tool.

[0022] According to an additional feature of the device according to the invention, the axis around which the tools can rotate is arranged at the intersection of the axis of displacement of the wire to be bent and a line joining the axes of the tools.

[0023] According to another additional feature of the device according to the invention, the bending tools consist of rollers.

[0024] According to another additional feature of the device according to the invention, the mechanical means consist of stepping motors associated with transmission means.

[0025] According to a particular embodiment of the device according to the invention, the bending head is mounted in rotation on an arm, which is, in turn, mounted pivotally with respect to feeding means for the wire to be bent.

BRIEF DESCRIPTION OF THE DPAWINGS

[0026] The advantages and features of the device according to the invention will become more evident by the following description referring to the attached drawing, which represents a non-restrictive embodiment. In the attached drawing:

[0027]FIG. 1 is a partial schematic view of the bending device according to the invention.

[0028]FIGS. 2a, 2 b, and 2 c are partial schematic views of the same device, during different stages of a bending operation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Referring to FIG. 1, one can see a schematic view of a bending device according to the invention, which comprises feeding means 1 for a wire 2 to be bent and a bending head 3.

[0030] The feeding means 1 is capable, through the action of the driving means, not shown, to pull the wire 2 axially, in the direction of the bending head 3, arrow X_(A), or in the opposite direction, arrow X_(B).

[0031] The bending head 3 comprises two bending tools, in this case two rollers 30 and 31, mounted freely pivoting on the shafts 32 and 33, respectively, and between which passes the wire 2 to be bent.

[0032] The bending head is mobile in rotation around an axis 34, parallel to the shafts 32 and 33 and, in this particular embodiment, located in the middle of the segment that connects the latter, this rotation being able to be performed clockwise, arrow Y_(A), or counterclockwise, arrow Y_(B).

[0033] In addition, the bending head 3 is mobile in rotation with respect to the feeding means 1, so as to describe a path in the form of an arch of a circle, clockwise, arrow Z_(A), or counterclockwise, arrow Z_(B).

[0034] One should note that it is also possible for the displacement of the bending head 3 to be performed rectilinearly. This variant is advantageous from the point of view of the programming of the computation and control means, but its construction is more complex.

[0035] The different movements are carried out through the use of mechanical means, not shown, such as for example stepping motors associated with transmission means, the operation of which is simultaneously governed by computation and control means permitting a superposition of these movements.

[0036] The superposition of these movements permits immobilizing the roller 30 or the roller 31 with respect to the wire 2 to be bent, while causing to rotate around the immobilized roller 30 or 31, the roller, 31 or 30, respectively, which pulls and bends the wire 2.

[0037] The strict superposition of the movements according to Y_(A), Y_(B), Z_(A) and Z_(B), permits the rotation of one of the rollers around de other one that is positioned on the axis parallel to the wire 2 without however remaining immobile. The immobilization is therefore achieved in a relative manner by the displacement of the wire 2 according to X_(A) and X_(B), which permits canceling the displacement of the rollers.

[0038] Referring to FIG. 2a, one can see that when bending the wire 2 in the counterclockwise direction, the roller 30 remains immobile, whereas the roller 31 rotates concentrically in relation to the roller 30 according to arrow B, in order to bend the wire 2.

[0039] The movement according to arrow B is achieved, commencing from a starting position such as the one shown in FIG. 1, by the superposition of a movement according to Y_(B) and Z_(B), as well as, successively, the movements according to X_(B) and X_(A)

[0040] The backward, then forward movement of the wire 2 according to X_(B) and X_(A) is required in that in the bending operation shown, the bending angle is larger than 90′.

[0041] In FIG. 2b, the bending head 3 is also placed in the starting position, whereas the wire 2 advances according to X_(A) in order to perform another bending operation.

[0042] Referring now to FIG. 2c, one can see an operation of bending of the wire 2 in the clockwise direction, thus in a relative manner, the roller 31 remains immobile, whereas the roller 30 rotates concentrically in relation to the roller 31 according to arrow A, in order to bend the wire 2.

[0043] The movement according to arrow A is achieved by the superposition of a movement according to Y_(A) and ZA, as well as, successively, the movements according to X_(B) and X_(A).

[0044] In the same way as for the bending operation shown in FIG. 2a, the forward and backward movement of the wire 2 according to X_(B) and X_(A) is required in that the bending angle is larger than 90° .

[0045] The bending device according to the invention permits carrying out the bending of the wire. Such a bending device uses tested mechanical means offering therefore a greater reliability. 

What is claimed:
 1. Wire bending device of the type comprising one bending head carrying two bending tools between which passes the wire to be bent, each one of said tools being capable of being driven in rotation concentrically around the other one, which is then fixed, characterized in that it comprises: mechanical means (1) capable of shifting the wire to be bent axially in one direction or another (X_(A), X_(B)), mechanical means capable of driving said bending tools (30, 31) in rotation, in botli directions (Y_(A), Y_(B)), around an axis (34) parallel to those (32, 33) of said tools (30, 31), mechanical means capable of shifting, in both directions Z_(A), Z_(B)), said tools in a plane perpendicular to the axis (34) around which the latter can rotate, and computation and control means capable of governing the simultaneous operation of said mechanical means, so as to obtain a superposition of the movements the latter generate.
 2. Device according to claim 1, characterized in that the axis (34) around which the tools (30, 31) can rotate is arranged at the intersection of the axis of displacement of the wire to be bent (2) and a line joining the axes of the tools (32, 33).
 3. Device according to claim 1 or claim 2, characterized in that the bending tools consist of rollers (30, 31).
 4. Device according to any of the preceding claims, characterized in that the mechanical means consist of stepping motors associated with transmission means.
 5. Device according to any of the preceding claims, characterized in that the bending head (3) is mounted in rotation on an arm, which is, in turn, mounted pivotally with respect to feeding means (1) for the wire to be bent (2). 